Fence posts are widely used in the construction of fences for a variety of purposes, such as animal management, property boundaries, snow barriers and the like. A popular type of fence post is made of steel and has a T-shaped cross section or a Y-shaped cross section. In the United States, these posts are commonly called "T-posts." The flat, vertical face has a spaced series of lugs or projections extending in a line opposite the rear or "leg" portion of the T-cross section. These lugs then are used to facilitate the attachment of wire (usually barbed wire), which is stretched along the posts and secured at intervals to braced line posts and corner posts. Bracing for the line posts and corner posts must be solid if the fence wire is to maintain its tension over a period of time.
The shape of metal T-posts or Y-posts does not facilitate simple attachment of braces with common hardware. Usually, the posts in a fence system which require braces are made of angle iron. Bracing of such posts is slow and cumbersome, since normally an angle iron brace is secured to the angle iron post with makeshift hardware. Frequently, a hole must be drilled through the post to secure the brace. Since fences of this type frequently located substantial distances from household power sources, portable generators or battery operated tools are necessary. Conventional bracing also typically secures the opposite or lower end of the brace in the soil, either with driven stakes or poured concrete. It is readily apparent that the bracing of T-posts or Y-posts in this manner is inefficient and costly.
Devices have been developed for attachment to a T-post, which clip onto the post through a type of spring action, or which are secured to the posts by means of threaded fasteners. Two patents disclosing devices for permitting the subsequent mounting of electric fence wire on metal T-posts are U.S. Pat. Nos. 3,820,758 (Berg) and 4,077,611 (Wilson). Both of these patents disclose a clip-on member made of insulating material which snaps over the post and is held in place by friction. Since the devices of both of these patents include a portion which rests on the post between the positioning lugs, vertical movement of the mounting device is restricted by the lugs located above and below the device.
The U.S. Pat. No. 3,874,640 (Wagner) discloses an attachment for placement on a T-post, between adjacent lugs, which facilitates the handling or tensioning of barbed wire, so that the wire may be stretched first and then raised out of the device and attached to the fence post. This is a temporary guide which is secured to the post only during the time the wire tensioning operation is effected.
The U.S. Pat. No. 3,670,468 (Cordell) is directed to a wedge for removably securing and aligning a T-post inside a larger pipe, for use in temporary fencing. The T-post loosely fits within the pipe; and the wedge then holds it in place vertically within the pipe, until removal of the wedge permits subsequent removal of the post. A substantial length of the post, including the positioning lugs on the front, is enclosed within the pipe at the bottom end of the post.
In U.S. Pat. No. 4,763,879 (Wasicek), a removable collar, which has a brace member welded to it, is placed over a T-post. The collar is of cylindrical shape and has an aperture in it for receiving a projection on the T-post when the collar is placed in the desired vertical position on the post. A wedge then is utilized to removably secure the collar to the post. Because the collar is cylindrical, the wedge makes contact with the collar in only two spaced-apart locations when it is driven between the collar and the post. In addition, because a single wedge is used, there is a tendency for the collar to tip or tilt on the post.
The U.S. Pat. No. 4,286,897 (Susskind) is similar in some respects to the device shown in the Wasicek patent. In the apparatus disclosed in Susskind, a clamp apparatus is used to secure a collar onto a cylindrical post. The clamp is a two-point or clamp or wedge which enters the collar from both the top and bottom, and further includes a bolt for drawing the two parts of the clamp toward one another to wedge the collar onto the post. The device of Susskind requires a number of different parts, but the tendency for the collar to tip which is present in Wasicek is overcome by the Susskind device.
The above identified U.S. Pat. No. 4,889,322 (Wagner) is an improvement over the devices shown in the Wasicek and Susskind patents. A collar having a rectangular internal configuration is placed between adjacent lugs on a T-post, and a wedge is driven between the rear of the T-post and the collar, to hold it in place. Because of the rectangular internal configuration, the wedge makes a substantial contact with the internal surface of the collar to firmly and securely hold the collar in place on the post. The wedge contacts the post at two points on the edge of the rear leg of the post. There still is a slight tendency for the collar to tip or tilt somewhat, because of the manner in which the wedge applies pressure between the post and a region of the collar located primarily along its upper edge.
The U.S. Pat. No. 1,330,808 (James) discloses a different type of fence post clamp for use on a cylindrical pipe fence post. The James fence post clamp has a generally cylindrical cross section which is open at one end, for clamping around a fence post. The clamp is held in place by pressure applied through the open edge. This open edge also includes a slot in it, and the end of a cross brace is inserted into the slot. The cross brace has a hole through it, as does the extension on the clamp. A bolt then is placed through the holes in the clamp and the end of the cross brace to secure the clamp onto the fence post and to secure the cross brace to the clamp. This device is not intended for use with a T-post or Y-post type of fence.
Another type of slide-on collar for use in a bracing system for fence posts is disclosed in the British patent to Holmes No. 598,417. This patent is directed to a bracing system for use with wooden fence posts having a rectangular cross section. A metal collar has an internal configuration permitting it to be slidably located at different vertical locations on the fence post. Once the desired location is determined, the collar is secured in place by a wood screw or other suitable fastener extending through an aperture in the collar into the post. The collar of Holmes clearly is not suitable for use with a T-post or Y-post fence system.
The above identified co-pending application is an improved double-action expansion wedge for mounting a collar of the type disclosed in U.S. Pat. No. 4,889,322 (Wagner). The collar member of the co-pending application, Ser. No. 07/413,285 now U.S. Pat. No. 4,979,724, wedges between the rear edge of the rear leg of the T-post and the inside of the collar member in a manner similar to that of U.S. Pat. No. 4,889,322 (Wagner), but because of the double action expansion cam construction, the tendency for the collar member to tilt is minimized. The wedge disclosed in this patent, however, is a two-piece wedge.
It is desirable to provide an improved attachment mechanism for mounting a collar on T-posts used in a fence system, and for overcoming the disadvantages of the prior art.